键盘扫描代码

Zedd · 发表于 2018-12-6 08:00

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键盘扫描代码

module key_board (clk, rst_n, row, col, data, valid, clk_1k);

      input clk;
      input rst_n;
      input [3:0] row;

      output reg [3:0] col;
      output reg [3:0] data;
      output reg valid;
      output reg clk_1k;

      reg [14:0] cnt;

      parameter T1ms = 24999;

      always @ (posedge clk or negedge rst_n)
            begin
                     if (!rst_n)
                              begin
                                    clk_1k <= 1'b1;
                                    cnt <= 15'd0;
                              end
                     else
                              begin
                                    if (cnt < T1ms)
                                             begin
                                                      cnt <= cnt + 15'd1;
                                             end
                                    else
                                             begin
                                                      cnt <= 15'd0;
                                                      clk_1k <= ~clk_1k;
                                             end
                              end
            end

      reg [7:0] row_col;
      reg [1:0] state;
      reg [4:0] count;

      always @ (posedge clk_1k or negedge rst_n)
            begin
                     if (!rst_n)
                              begin
                                    col <= 4'b0000;
                                    row_col <= 8'd0;
                                    state <= 0;
                                    valid <= 0;
                                    count <= 0;
                              end
                     else
                              begin
                                    case (state)
                                             0 : begin
                                                            if (row == 4'b1111)
                                                                     begin
                                                                              col <= 4'b0000;
                                                                     end
                                                            else
                                                                     begin
                                                                              state <= 1;
                                                                     end
                                                      end

                                             1 : begin
                                                            if (row == 4'b1111)
                                                                     begin
                                                                              state <= 0;
                                                                              count <= 0;
                                                                     end
                                                            else
                                                                     begin
                                                                              if (count < 19)
                                                                                    begin
                                                                                             count <= count + 1;
                                                                                    end
                                                                              else
                                                                                    begin
                                                                                             count <= 0;
                                                                                             state <= 2;
                                                                                             col <= 4'b0111;
                                                                                    end
                                                                     end
                                                      end

                                             2 : begin
                                                            if (row == 4'b1111)
                                                                     begin
                                                                              col <= {col[2:0],col[3]};
                                                                              state <= 2;
                                                                     end
                                                            else
                                                                     begin
                                                                              row_col <= {row,col};
                                                                              state <= 3;
                                                                              valid <= 1;
                                                                     end
                                                      end

                                             3 : begin
                                                            if (row == 4'b1111)
                                                                     begin
                                                                              state <= 0;
                                                                              valid <= 0;
                                                                     end
                                                            else
                                                                     begin
                                                                              valid <= 0;
                                                                              state <= 3;
                                                                     end
                                                      end


                                             default : state <= 0;

                                    endcase
                              end
            end

      always @ (*)
            begin
                     case (row_col)
                              8'b0111_0111 : data = 4'hf;
                              8'b0111_1011 : data = 4'he;
                              8'b0111_1101 : data = 4'hd;
                              8'b0111_1110 : data = 4'hc;

                              8'b1011_0111 : data = 4'hb;
                              8'b1011_1011 : data = 4'ha;
                              8'b1011_1101 : data = 4'h9;
                              8'b1011_1110 : data = 4'h8;

                              8'b1101_0111 : data = 4'h7;
                              8'b1101_1011 : data = 4'h6;
                              8'b1101_1101 : data = 4'h5;
                              8'b1101_1110 : data = 4'h4;

                              8'b1110_0111 : data = 4'h3;
                              8'b1110_1011 : data = 4'h2;
                              8'b1110_1101 : data = 4'h1;
                              8'b1110_1110 : data = 4'h0;

                              default : data = 4'h0;
                     endcase
            end

endmodule

kinidrily · 发表于 2018-12-6 11:41

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